1. Field of Invention
The present invention relates to a motor control apparatus and a motor control method. More particularly, the present invention relates to a motor control apparatus and a motor control method that can determine whether the motor is in a back pressure area so as to provide different rotation-speed control signals, thereby increasing the efficiency of the motor.
2. Related Art
The motor control technology has been developed for a long time. For example, the circuit can be applied to the motor for controlling the rotation of the motor. Moreover, the circuit can further be used to adjust the rotation speed of the motor. As shown in FIG. 1, a conventional motor control apparatus 1A mainly includes a driver circuit 10 and a coil switching circuit 12, which form an open-loop control circuit. The driver circuit 10 is used to drive the motor 22 to rotate, and controls the close/open of the coil switch circuit 14 according to a duty cycle of a pulse width modulation signal T. Accordingly, the current direction of the coil set 21 of the motor 2 can be switched between two adjacent phases so as to adjust and control the rotation speed of the motor 2. As shown in FIG. 2, another conventional motor control apparatus 1B mainly includes a driver circuit 10, a coil switching circuit 12 and a rotation-speed detecting circuit 14, which form a close-loop control circuit. The configuration of the rotation-speed detecting circuit 14 can allow the motor have a duty cycle (TS) switch at full speed. The duty cycle (TS) and the rotation-speed detecting circuit 14 have a corresponding function. That is, the duty cycle (TS) can be changed according to the detecting of the rotation-speed detecting circuit 14. When the detected rotation speed increases, the duty cycle (TS) also increase until reaching 100%. Thus, after adding the rotation-speed detecting circuit 14, the rotation speed of the motor 2 can be increased after the motor 2 enters the back-pressure area, thereby achieving the effect of increasing airflow quantity and airflow pressure.
Regarding to the open-loop control circuit of FIG. 1, since the rotation speed is controlled by the pulse width modulation signal T when the fan enters the back-pressure area (high duty cycle and high rotation speed), the effect of the airflow pressure and airflow quantity (PQ value) will be affected. Regarding to the close-loop control circuit of FIG. 2, the rotation speed of the motor 2 is affected by the rotation-speed detecting circuit 14 and thus be adjusted when the fan is in the low duty cycle (low rotation speed), so that the fan can not have accurate rotation speed.